This invention relates to novel methods, apparatus and products for verification of the effectiveness of thermal sterilizing procedures. In particular, this invention is concerned with obtaining an indication of desired thermal sterilization which is available upon completion of a thermal sterilizing cycle free of any delay for incubating or measuring the growth of microbial organisms. A specific embodiment of the invention is concerned with a compatible indicator material for providing an indication of sterility upon completion of a cycle and, also, after an incubating delay period for growth of microbes so as to be capable of providing dual indication of the effectiveness of a thermal sterilizing cycle.
Commercial verification of thermal sterilization has been limited to evaluations after exposure to a thermal sterilizing cycle and after a predetermined period of incubation of a culture medium, to determine whether exposed microbes in the culture medium survived the thermal exposure. A predetermined period of incubation of two to about seven days under controlled conditions was necessary, after a sterilizing cycle was completed, for such microbial life testing.
Under those procedures, a sterilizer load was required to be quarantined until verification of sterilization was achieved through analysis of spore incubation procedures and results. Such delays cause difficulties for most laboratories, hospitals and similar institutions due to space limitations, supply inventories and time costs.
The present invention provides for elimination of such delayed verification testing for thermal sterilization results by enabling direct verification testing upon completion of a thermal sterilizing cycle, free of a requirement for an incubation period.
A load, comprising materials to be sterilized, is interspersed with test indicator ampoules containing a novel indicator material of the invention. Upon completion of a thermal sterilizing cycle, such indicator material enables direct verification of the effectiveness of the sterilizing cycle.
In carrying out such direct indication and verification procedures, a system is provided which measures a property of such novel indicator material, which is responsive to chemical change during thermal exposure in a sterilizing cycle; and, measurement of such property and verification of sterilization effectiveness are available directly upon completion of a thermal sterilizing cycle.
In a specific embodiment of the invention, the indicator material responsive to chemical change comprises a newly developed growth nutrient composition which not only enables direct verification of sterilizing effectiveness by such direct measurement of chemical change; but, also, enables verification of sterilizing effectiveness by providing for biological change following a spore incubation period.
The above and other advantages and contributions of the invention are considered in greater detail with references to the accompanying drawings.